Frangible bullet

ABSTRACT

A frangible hollow point bullet is disclosed. The bullet (or slug) is formed from a frangible material such as sintered copper to provide a bullet-shaped body. A plurality of coaxial, substantially cylindrical cavities having progressively decreasing bore diameters are formed in the nose of the bullet-shaped body, extending rearwardly therefrom, to provide a bullet that both expands and fragments in a semicontrolled fashion upon impact with a target. In a preferred embodiment, at least one of the coaxial cavities is multiply scored to provide a substantially symmetric fragmentation pattern and a controlled and uniform fragment size. Controlling the aggregate depth of the coaxial cavities enables the retention of a recoverable base or shank that is suitable for ballistic investigation following bullet impact. Bullets and slugs, made in accordance with the present invention, have standard calibers and, when incorporated into conventional cartridges and shotgun shell casings respectively, may be fired at subsonic, sonic or supersonic velocities by conventional weapons.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to ammunition and moreparticularly to hollow point bullets or slugs and pellets comprising acartridge or similar projectile propulsion device.

[0003] 2. Description of the Prior Art

[0004] Recent events, particularly the hijacking of airplanes byterrorists and the subsequent loss of life in the United States ofAmerica, most notably in New York, Pennsylvania and Virginia, havegenerated a need for new ideas for preventing airplane hijacking. Forexample, it has been proposed that one or more armed air marshalsaccompany scheduled airline flights to intervene in the event of anattempted hijacking. Another proposed solution is to arm pilots withweapons capable of selectively and accurately dispensing lethal forceagainst a hijacker. A disadvantage with discharging a conventionalweapon on an airplane wherein prior art bullets are the projectile isthe danger posed by the bullet passing through the hijacker and strikinganother person or causing damage to the avionics.

[0005] The nose portion of a hollow point bullet expands upon impactwith a target media thereby increasing the energy transfer capabilitiesof the bullet. Typically, this expansion results in a number of petalsof metal being formed as the nose portion folds back upon itself,thereby increasing the effective diameter of the bullet. This expansionand resultant petal formation is referred to as “mushrooming.” A hollowpoint bullet may be solid or jacketed. A solid bullet typicallycomprises a solid piece of metal, such as lead or copper. A jacketedbullet typically comprises a lead core surrounded by a harder metal,such as brass. The jacket is relatively hard and slick, compared to thelead of the core, so the bullet is more resistant to mechanicaldeformation by the action of the gun as compared to the solid bullet.

[0006] Swank, in U.S. Pat. No. 5,943,749, discloses a bullet comprisinga slug of generally solid material having an outer surface and a leadingend portion having a cavity therein. A plurality of grooves are formedon the outer surface of the end portion. The end portion of the slug iscontoured so that the bullet has a predetermined shape. A plurality ofslits may be formed through at least a portion of each of the pluralityof grooves. Preferably, the plurality of grooves and slits are formedsubstantially simultaneously. The slits are formed around a peripheraledge of the leading end portion of the slug. A plurality of projections,may be formed which extend into the cavity adjacent to the slits. Eachof the slits may be formed at an angle with respect to a longitudinalaxis of the slug to form each of the projections. The cavity in theleading end portion has a truncated cone geometry. Hollow Point (HP)projectiles can expand too quickly, resulting in poor penetration, orcan only partially expand, leading to over penetration of a target andreduced energy transfer to the target. In addition, hollow point bulletscan fail to expand, leading to severe over penetration or pass through.

[0007] Benini, in U.S. Pat. No. 6,263,798, discloses a frangible bulletand a method for making it. The frangible bullet is formed from amixture of metal particles and metal or metalloid binder material whichis compacted into the desired shape and heated to a target temperature.The target temperature is selected such that it is above the temperaturerequired to form at least one intermetallic compound (but below thetemperature of joining of the metal particles by sintering), and belowthe temperature of formation of substantial amounts of a ductile alloyof the metal of the particles and the metal or metalloid bindermaterial. The bullet is then cooled. When such articles are formed intobullets and fired at a target possessed of substantial mass, they havesufficient strength to maintain their integrity during firing butdisintegrate into powder on impact. In addition, the bullet may comprisea variety of metals other than lead.

[0008] Huffman, in U.S. Pat. No. 6,115,894, discloses an armor-piercingfrangible bullet, and provides a historic summary of bullet developmentas well as a summary of test data obtained for commercially availablesmall arms ammunition. In particular applications, it may be desirableto provide a hollow point, frangible bullet that can be subjected toballistic inspection following impact with a target. Ballistic testingof a bullet requires that a substantial portion adjacent the base of abullet (i.e., a shank) remain intact when presented for testing. Thus,it is desirable to provide a bullet that may be designed to possessattributes of both hollow point and frangible bullets and which, uponimpact with a target, retains a recoverable shank of predetermined sizethat is suitable for ballistic characterization and identification.

[0009] Most ammunition projectiles, particularly the newer non-leadfrangible projectiles, perform poorly in the sub-sonic range. Manyammunition manufacturers use high velocities to enhance the frangibility(break up) of the bullet upon impact. Prior art frangible projectilescan fail to fragment if the chemical process used to make the bullet isnot carefully controlled. In addition, such frangible bullets operatebest when fired at very high velocities, and are loaded by ammunitionmanufacturers at high pressures. Further, the fragmentation pattern israndom and generally forms asymmetric clusters with respect to thedirection of the primary wound channel.

[0010] While both frangible bullets and mushrooming hollow point bulletsare known in the art, and wherein each has unique attributes thatrecommend it for specific situations, there continues to be a presentand urgent need for improved bullets that can be fired by conventionalweapons such as pistols and will minimize the danger of collateraldamage in the event of a hijacking or similar situation whereinshoot-through injuries to innocent non-target people is probable.

SUMMARY OF THE INVENTION

[0011] It is a primary object of the present invention to provide afrangible hollow point bullet adapted to be used in conventional smallarms cartridges.

[0012] It is another object of the invention to provide a bullet meetingthe primary objective, set forth above, wherein a shank portion of thebullet that is suitable for ballistic analysis is recoverable afterimpact of the bullet with a target.

[0013] It is a further object of the invention to provide a frangiblehollow point bullet that fragments on impact with a target and whereinthe size of the fragments is substantially controllable and uniform.

[0014] It is yet a further object of the invention to provide afrangible bullet that fragments upon impact with a target and whereinthe spatial distribution of bullet fragments is substantially symmetricthrough a solid angle centered on the trajectory of the bullet prior toimpact with the target.

[0015] The above objectives of the invention are met by a substantiallybullet-shaped projectile having a leading end, a trailing end and afrangible body portion therebetween. The projectile has a hollow cavityopening onto the leading end of the body portion and extendingrearwardly therefrom into the body portion. In a first preferredembodiment, the hollow cavity comprises a plurality of coaxialcylindrical cavities, wherein the diameter of each rearwardly adjacentcylindrical cavity comprising the hollow cavity decreases stepwise, indiscrete increments, in a direction rearward of said leading end. In thefirst preferred embodiment of the projectile, at least one of thecylindrical cavities has a cavity wall bearing stress risers thereon. Ina most preferred embodiment of the projectile, all of the cylindricalcavities comprising the hollow cavity have a pattern of stress risers onthe wall thereof. Examples of suitable patterns of stress risers includea diamond-shaped pattern of grooves, a plurality of parallel grooves, aplurality of horizontal and or vertical grooves and so forth. The depthof the hollow cavity relative to the axial length of the projectile canbe varied to control the fragmentation pattern and the size of theintact, recoverable base or shank. The inclusion of stress risers withinthe hollow cavity provides means for controlling fragment size uponimpact. In a second preferred embodiment of the projectiles, the cavityin the leading end of the projectile comprises a plurality of concentricconical cavities having decreasing diameter in the direction of thetrailing end of the projectile. Preferred projectiles include bulletsand shotgun slugs and pellets. In an embodiment of a shotgun slug havinga hollow cavity in the rearward trailing end thereof, the wall of thehollow cavity includes stress risers thereon. The outer lateral surfaceof the projectile is preferably smooth but may be scored to bear apattern. In all embodiments, the leading end of the hollow cavity may beconically flared outwardly.

[0016] The features of the invention believed to be novel are set forthwith particularity in the appended claims. However the invention itself,both as to organization and method of operation, together with furtherobjects and advantages thereof may be best understood by reference tothe following description taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 is a side elevational view of a cartridge comprising abullet in accordance with a first embodiment of the present invention.

[0018]FIG. 2 is a cross-sectional view of the cartridge of FIG. 1 takenalong section line 2-2 wherein the cartridge is center firing.

[0019]FIG. 3 is a cross-sectional view of the cartridge of FIG. 1 takenalong section line 2-2 wherein the cartridge is rim firing.

[0020]FIG. 4 is a cross-sectional view of a frangible hollow pointbullet having two coaxial cavities in accordance with a two-cavityembodiment of the present invention.

[0021]FIG. 5 is a cross-secional view of a frangible hollow point bullethaving three coaxial cavities in accordance with a three-cavityembodiment of the present invention.

[0022]FIG. 6 is a cross-sectional view of a three-cavity embodiment of afrangible, hollow point bullet wherein the walls of the cavities havebeen skived to provide a grooved, diamond-like pattern thereon.

[0023]FIG. 7 is a cross-sectional view of a three-cavity frangible,hollow point shotgun slug wherein the three cavities have been skived bya tap to produce a plurality of parallel slanting grooves on the cavitywalls.

[0024]FIG. 8 is a cross-sectional view of a multicavity, frangible,hollow point bullet illustrating a variety of stress riser patternsskived on the respective cavity walls.

[0025]FIG. 9 is a cross-secional view of a frangible hollow point bullethaving three coaxial conical cavities in accordance with a three-conicalcavity embodiment of the present invention.

[0026]FIG. 10 is a cross-secional view of a frangible hollow pointbullet having three coaxial conical cavities in accordance with athree-conical cavity embodiment of the present invention wherein thewalls of the conical cavities are skived.

[0027]FIG. 11 is a cross-sectional view of a frangible hollow pointbullet having three coaxial conical cavities in accordance with athree-conical cavity embodiment of the present invention wherein thewalls of one or more of the respective conical cavities are indented.

[0028]FIG. 12 is a cross-sectional view of a wad used to propel one ormore projectiles such as pellets from a shotgun shell wherein the wadcomprises a compressible trailing portion and a cup-shaped leadingportion that is slit.

[0029]FIG. 13 is a cross-sectional view of a wad used to propel one ormore projectiles such as pellets from a shotgun shell similar to the wadshown in FIG. 12 wherein the wad comprises a compressible trailingportion and a cup-shaped leading portion that is only partially slit.

[0030]FIG. 14 is a cross-sectional view of a wad similar to the wadsshown in FIGS. 12 and 13 but wherein the wad comprises a compressibletrailing portion and a cup-shaped leading portion that is unslit andcontains a foam or a gel.

[0031]FIG. 15 is a cross-sectional view of a wad used to propel one ormore projectiles such as pellets from a shotgun shell wherein the wadcomprises a noncompressible trailing portion and a cup-shaped leadingportion that contains compacted particles.

[0032]FIG. 16 is a cross-sectional view of a wad used to propel one ormore projectiles such as pellets from a shotgun shell wherein the wadcomprises a noncompressible trailing portion and a leading portion thatcontains a foam or a gel.

[0033]FIG. 17 is a cross-sectional view of a wad used to propel one ormore projectiles such as pellets from a shotgun shell wherein the wadcomprises a noncompressible trailing portion and a noncompressible,unslit leading portion.

[0034]FIGS. 18-23 are illustrative of the manner in which the surfacemorphology of shotgun shell pellets can be modified to produce differenteffects prior to, during and after impact with a target.

[0035]FIG. 24 is a cross-sectional view of a hollow point shotgun shellprojectile or slug wherein an insert within the trailing end of theprojectile comprises one or more straight fins to stabilize thetrajectory of the slug.

[0036]FIG. 25 is a cross-sectional view of a hollow point shotgun shellprojectile wherein an insert within the trailing end of the projectilecomprises one or more angled fins to rotate the projectile and stabilizethe trajectory of the slug.

[0037]FIG. 26 is a cross-sectional view of a hollow point shotgun shellprojectile wherein an insert within the trailing end of the projectilecomprises one or more curved fins to rotate the projectile and stabilizethe trajectory of the slug.

[0038]FIG. 27 is a cross-sectional view of a shotgun shell having acompressible wad and a plurality of pellets with cavities thereinembedded within a gel or a foam.

[0039]FIG. 28 is a cross-sectional view of a shotgun shell comprising acompressible wad and a helically finned, hollow point projectile havinga conical double cavity with indentations in a leading end thereof.

[0040]FIG. 29 is a cross-sectional view of a shotgun shell having acompressible wad and a plurality of hollow point bullets, with orwithout scoring, laterally enclosed in a sabot.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] A cartridge 10 comprising a frangible, three-cavity, hollow pointbullet 11 in accordance with a three-cavity embodiment of the presentinvention is shown in side elevational view in FIG. 1. The cartridge 10includes a case 12 encasing explosive material for expelling the bullet11 from the case 12. The case 12 has a leading end 13 which houses thebullet 11 and a trailing end 14 housing a primer 21 (FIG. 2) thatexplodes upon mechanical impact.

[0042] Turning now to FIG. 2, the cartridge 10 of FIG. 1 is shown incross-sectional view, taken along section line 2-2. If the cartridge 10is center firing, the primer 21 is axially disposed on the trailing end14 of the case 12 as shown. Forward of the primer is an explosive charge22 such as gunpowder. A bullet 11 is pressure fitted into the leadingend 13 of the case 12. The bullet 11 has three cylindrical, coaxialcavities in the nose thereof: an outer cavity 23, a middle cavity 24 andan inner cavity 25, the respective cavities having progressively smallerdiameters. A rim fire cartridge 30 is shown in cross-sectional view inFIG. 3. The construction of the cartridge 30 is similar to the cartridge10 of FIG. 1 except that primer 21 is incorporated into the trailing end14 of the case.

[0043] A key feature of all embodiments of the frangible bullet of thepresent invention is the presence of more than one coaxial cavity in thenose of the bullet, such as illustrated, for example, in FIGS. 4 and 5,and/or the presence of a scored pattern on the wall of at least onecavity. Prior art hollow point bullets, such as described earlier, havegrooves on the outer surface of the nose of the bullet to providecontrolled mushrooming. The present inventors have found that for hollowpoint frangible bullets, the fragmentation pattern can be controlled byskiving the wall of one or more of the cavities comprising the hollowpoint. The skived pattern may take any of the forms shown in FIGS. 6-8.FIG. 6 shows a three-cavity embodiment of a frangible, hollow pointbullet having a diamond-shaped pattern skived on the cavity walls. FIG.7 shows a three-cavity embodiment of a frangible, hollow point slug 70for a shotgun shell having a diagonal set of parallel grooves skived onthe cavity walls and a diagonal set of parallel grooves in a rearwardcavity 71. FIG. 8 illustrated a four-cavity embodiment 80 of afrangible, hollow point bullet having a pattern comprising a pluralityof parallel diagonal grooves 81, a plurality of vertical grooves 82, aplurality of horizontal grooves 83 and a diamond-shaped pattern 84skived on the respective cavity walls. While particular skived patternsare illustrated on the cavity wall, such patterns are provided for thepurpose of example. It is contemplated that other patterns may also beskived on the wall of a cavity.

[0044] When drilling, molding, or otherwise creating the cavities in afrangible bullet of the present invention wherein uniform fragment sizeis an important consideration, and the (multiple) cavities havedifferent diameters and depths, the bore/depth ratio of the cavity islimited. If the cavities are drilled too deep, fragment size may benonuniform, and the accuracy of the bullet is reduced. The use ofmultiple cavities in the nose of a bullet, each cavity having a moderatedepth and bore diameter, provides a more uniform fragment size. Inaddition, by increasing the number of cavity sizes employed to createthe hollow point, the greater the effectiveness of the stress risers(i.e., the pattern of grooves on the cavity walls) for controllingfragmentation of the bullet. Bullet stability (accuracy) can beadversely affected by an excessive number of cavities in order tominimize the size of the residual base or shank. Reduction of theresidual base (shank) to a minimum mass (even to zero) can be achievedwith multiple diameter holes, however a loss of bullet accuracy mayoccur. The inclusion of stress risers on the interior wall of thecavity(ies) of a frangible bullet in accordance with the presentinvention, by scoring, forming or skiving a pattern of grooves thereon,or forming a pattern of indented “dimples” thereon greatly enhance theuniformity of fragment size upon impact. The leading end of the hollowcavity may be conically flared. A hollow point projectile having ahollow, axially symetric cavity that comprises three cylindricalcavities with decreasing bore diameters, that include stress risers onthe cavity walls, provides a controllable breakup pattern as desired.Since the fragmentation of a frangible, multicavity hollow point bulletin accordance with the present invention will not substantially extendrearwardly of the axial cavity, the residual mass of the base (shank)can be determined by the total depth of the cavity.

[0045] The embodiments of a frangible bullet described herein allowsconsistent and controllable performance as to penetration, frangibility,and fragment size and shape for hollow point bullets comprised ofvarious materials at sub-sonic, sonic, and super-sonic velocities and invarious ammunition types. The frangible bullet/projectile in accordancewith the present invention may comprise, but is not limited to anysintered, unsintered, cold compacted, cast, or cured bullets. Frangible,hollow point bullets in accordance with the present invention have anaxially symmetric hollow cavity comprising a pattern of intersecting(diamond pattern) and/or non-intersecting stress risers skived orotherwise formed on the cavity wall. The shape of the nose cavity andpattern of the stress risers can be used to pre-determine fragment size,fragmentation pattern and action. In addition, the leading end of thehollow cavity may be conically flared without departing from the scopeof the present invention.

[0046] With reference now to FIGS. 9-11, a bullet 11 having a pluralityof conical cavities in a leading end thereof is illustrated incross-sectional view. FIG. 9 illustrates a bullet 11 having two coaxialconical cavities 90 and 91 in the leading end thereof. The innermostcavity 90 has a smaller outer diameter than the outermost cavity 91 witha step 94 therebetween. The advantage of hollow point bullets havingconical recesses therein is that the cavities 90 and 91, as well as theflared leading edge 92, can be easily molded into the bullet during themanufacturing process. The walls 93 of the cavities 90 and 91 are smoothin FIG. 9, skived 100 in FIG. 10, or may bear a pattern of indentationsas shown at 110 in FIG. 11. The skiving 100 and indentations 110 can beformed in the wall of cavities 90 and 91 by molding (the skived pattern)or by forcing a conical scoring tool thereinto (indentations).

[0047] When constructing shotgun shells, a thickness of wadding materialis normally interposed between the projectile(s) and the powderpropellant. Some examples of a suitable wadding material in accordancewith a further aspect of the present invention are illustrated incross-sectional view at numeral 120 in FIGS. 12-17. With reference toFIG. 12, a thickness of wadding 120 comprises a compressible portion 121housed within a substantially noncompressible cup portion 122. Thenoncompressible cup portion, usually plastic, may have at least one slit123 therein to permit the cup-shaped leading portion of the wad to openwhen it is ejected from the shell, thereby increasing itscross-sectional area and slowing it down to lag behind the projectile(s)(not shown in FIGS. 12-17) housed therewithin after the wad leaves thebarrel of a shotgun. The depth of the slit 123 as well as the number ofslits may be varied in order to control the pattern of pellets propelledfrom the shotgun shell. An example of a wadding 120 that comprises acompressible portion 121 and a noncompressible cup portion 122 that haspartial slit(s) 123 therein is illustrated in cross-sectional view inFIG. 13, and a shotgun shell having an unslit noncompressible cupportion filled with a foam or gel 163 and a compressible portion 121 isshown in FIG. 14.

[0048] The wad 120 may also comprise a noncompressible portion 151 and anoncompressible cup-shaped portion 122 as shown in FIGS. 15-17. Thepellets 152 may be packed in the noncompressible cup-shaped portion 122with a particle buffer 153 or a foam or gel buffer 163 therebetween asshown in FIG. 16, or with no buffer therebetween as shown in FIG. 17.For clarity, the pellets are not shown in FIGS. 12-17. As with theprevious embodiments of a wad shown in FIGS. 12-14, the cup portion 122may be slit, partially slit or unslit, depending on the application.

[0049] Examples of frangible pellets that are suitable for use asprojectiles that can be housed within the noncompressible cup portion122 of a shotgun shell are shown in plan view in FIGS. 18-23. A pellethaving a plurality of dimples 180 in the surface thereof is shown inFIG. 18. FIG. 19 shows a pellet having three orthogonal bores 190drilled therethrough. FIG. 20 shows a pellet having a plurality ofconical cavities 200 in the surface thereof. The wall of the cavities200 may be smooth, skived or bear indentations thereon. A pellet havingtwo orthogonal circumferential grooves 210 on the surface thereof isillustrated in FIG. 21. FIG. 22 shows a pellet having an outer surfacebearing a pattern such as polygons 220 or similar geometric patterns. Apellet having a plurality of cylindrical cavities 230 in the surfacethereof is illustrated in FIG. 23. Again, as with the pellet shown inFIG. 20, the wall of the cavities can be smooth, skived or bearindentations thereon. Such modifications of the pellet surface as, forexample, shown in FIGS. 18-23, can be used to alter the aerodynamicbehavior of the pellet(s) and/or serve as stress risers to establish apredetermined pattern of disintegration of the pellet(s) upon impactwith a target.

[0050] The aerodynamic behavior of hollow point projectiles such as theshotgun slug 240 illustrated in FIG. 24, or the solid-nosed shotgunslugs 250 illustrated in cross-sectional view in FIGS. 25 and 26, may bemodified by the addition of fins to the trailing end thereof. Withreference now to FIG. 24, a hollow point shotgun slug 240 has a pair ofconical cavities 91 and 90 coaxially disposed on a leading end of a body245 and an insert 241 affixed to a cavity 242 in a trailing end of thebody 245 by means of an adhesive 243. The trailing end of the insert 241has a plurality of fins 244 projecting rearwardly therefrom that serveto stabilize the trajectory of the slug 240 through the air. Asolid-point slug is indicated at 250 in FIG. 25 having an insert 241that screws into the cavity 242, a thread 251 providing means forattaching the insert 241 to the body 245 of the slug 250. The insert 241has a plurality of tilted fins projecting rearwardly therefrom to impartrotary motion to the slug 250. FIG. 26 shows a slug similar to the slugillustrated in FIG. 25 but wherein the fins 262 are helical and projectrearwardly from the slug to impart rotary motion thereto when propelledthrough the air. The insert is attached to the body 245 by means of a“C-ring” or hog ring 261 that fits within an annular groove 260 in thebody 245. It will be understood and appreciated by the artisan thatfinned inserts can be used with either hollow point or solid pointbullets and that various methods may be used to attach the fins to thebody of the slug.

[0051] An example of a shotgun shell 270 comprising a plurality ofpellets such as plain spherical pellets or the novel pellets illustratedin FIGS. 18-23 is shown in cross-sectional view in FIG. 27. The shotgunshell 270 comprises a case 271 having a base 272 that supports animpact-ignitable primer 273. A charge of explosive 274 is disposedbetween the primer 273 and a compressible wad 275. A plurality ofpellets 276 embedded in a foam or a gel 277 is disposed between the wad275 and the leading end of the case 271. A further example of a shotgunshell in accordance with the present invention is indicated at numeral280 in FIG. 28. As with the shotgun shell 270, discussed above, theshotgun shell 280 comprises a case 271 having a trailing end 272 thatsupports a primer 273, and houses an explosive charge 274 and a wad 275.A hollow point slug having double conical cavities 90 and 91 in aleading end thereof is disposed between the wad 275 and the open leadingend of the case. The slug 281 has a finned insert 241 affixed viathreads to a cavity in the trailing end of the slug. The helical fins262 cause the slug 281 to spin when fired.

[0052] A further application of the frangible, hollow point projectilesof the present invention is illustrated in FIG. 29. FIG. 29 is across-sectional view of a shotgun shell 290 having a wad 120 comprisinga compressible portion 121, a noncompressible cylindrical sabot 293 anda plurality of hollow point slugs 294 and 295 bounded laterally by thesabot 293 within the shell 290. The sabot 293 is a tubular sleeve,usually plastic, having a slit 297 coextensive with the length thereofand an axial bore 296 equal to the outer diameter of the slugs orbullets 294 and 295. The sabot enables small diameter projectiles to befired from a gun having a larger bore.

[0053] While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. For example, thelateral outer surface of any of the frangible, hollow point projectilesdisclosed herein may be scored or otherwise patterned. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What we claim is:
 1. A substantially bullet-shaped projectile comprisinga body having a leading end, a trailing end and a frangible body portiontherebetween, and a plurality of cavities having cylindrical wallsextending rearwardly into said body portion from said leading end, thediameter of said cylindrical walls of each cavity comprising saidplurality of cavities being progressively smaller in a directionrearward of said leading end.
 2. The projectile in accordance with claim1 further comprising a plurality of grooves on said cylindrical wall ofat least one of said plurality of cavities.
 3. The projectile of claim 1wherein said projectile is a bullet.
 4. The projectile of claim 2wherein said projectile is a bullet.
 5. The projectile in accordancewith claim 1 further comprising a plurality of grooves on saidcylindrical wall of each cavity comprising said plurality of cavities.6. The projectile of claim 5 wherein said projectile is a bullet.
 7. Aprojectile in accordance with claim 1 wherein said body portion has asmooth outer surface.
 8. A projectile in accordance with claim 2 whereinsaid body portion has a smooth outer surface.
 9. A substantiallybullet-shaped projectile having a leading end, a trailing end and afrangible body portion therebetween, and a hollow cavity in said leadingend of said body portion, said hollow cavity comprising a plurality ofcoaxial cylindrical cavities extending rearwardly into said body portionfrom said leading end, the diameter of each cylindrical cavitycomprising said plurality of cavities decreasing stepwise in discreteincrements in a direction rearward of said leading end.
 10. A projectilein accordance with claim 9 wherein at least one said cylindrical cavitycomprising said hollow cavity has a cavity wall bearing stress risersthereon.
 11. A cartridge comprising a projectile in accordance withclaim
 9. 12. A cartridge comprising a projectile in accordance withclaim
 10. 13. A substantially bullet-shaped projectile having a leadingend, a trailing end and a frangible body portion therebetween, and ahollow cavity in said leading end of said body portion, said hollowcavity comprising a plurality of coaxial conical cavities extendingrearwardly into said body portion from said leading end, the diameter ofeach conical cavity comprising said plurality of cavities decreasingstepwise in discrete increments in a direction rearward of said leadingend.
 14. A projectile in accordance with claim 13 wherein at least onesaid conical cavity comprising said hollow cavity has a cavity wallbearing stress risers thereon.
 15. A cartridge comprising a projectilein accordance with claim
 13. 16. A cartridge comprising a projectile inaccordance with claim
 14. 17. A shotgun shell comprising a plurality ofpellets wherein each pellet comprising said plurality of pellets has anexterior surface with a plurality of cavities thereon.
 18. A shotgunshell comprising a plurality of pellets embedded within a foam or a gel.19. A shotgun shell comprising a projectile having a leading end and atrailing end wherein said trailing end has a plurality of fins attachedthereto.